Benzinga's Top Pre-Market Losers

Prosensa Holding NV RNA dipped 74.54% to $6.11 in the pre-market session on failed duchenne muscular dystrophy study. AK Steel Holding AKS shares fell 10.59% to $3.97 in the pre-market trading after the company projected wider loss for the third quarter. Sarepta Therapeutics SRPT shares dropped 8.69% to $33.50 in pre-market trading on GlaxoSmithKline GSK trial miss. Darden Restaurants DRI dipped 5.48% to $46.60 in the pre-market session after the company reported downbeat Q1 results and announced the retirement of its COO.